1. Field of the Invention
The present invention relates to telecommunications and, more particularly, to voice-over-broadband networks and voice emergency systems.
2. Description of the Related Art
In conventional POTS (plain old telephone system) networks, analog telephones transmit and receive voice signals via a telephone company's local central office (CO). Recently, it has become possible to use various voice communication devices, including Internet protocol (IP) phones, appropriately configured PCs, as well as POTS analog phones, to send and receive voice calls over the Internet.
To send and receive calls over the Internet using POTS phones, transcoding must be performed between the analog signals associated with the POTS phones and the digital packetized signals used to carry voice calls over the Internet. In such a configuration, an analog telephone is typically connected to a voice-over-IP (VoIP) gateway via a POTS central office emulator (PCOE). The PCOE handles the analog interface to the POTS phone to make it appear to the POTS phone as if it is directly connected to a CO. This interface includes ring assertion, tip/ring powering, offhook/onhook detection, and dialtone generation. The PCOE passes analog signals between the POTS phone and the VoIP gateway. The VoIP gateway transcodes between analog signals associated with the PCOE and digital IP packetized signals compatible with the VoIP protocol. The VoIP gateway further interfaces the VoIP data to the Internet via a broadband access device such as a cable modem.
Service providers are building data-centric networks to support digital voice-over-broadband (VoBB) services (e.g., VoIP). However, to become a local exchange carrier (LEC), a service provider must comply with local regulations, including those that require them to offer emergency (e.g., 911) services to all subscribers.
While VoIP is now routinely deployed by LECs, the unchanged 911 tandems that handle emergency calls have fallen years behind the current technologies. Still widely in use, many 911 tandems do not support IP-based protocols, and these tandems continue to require trunking via multi-frequency (MF) tones. Complicating the matter is the protocol uniqueness of the operator services that 911 tandems supply. LECs face the dilemma of how to comply with mandatory 911 regulations without investing in expensive network upgrades. Meanwhile, 911 services remain unsupported for users of broadband voice.
While the LECs struggle with regulatory compliance, businesses and consumers continue to demand the features associated with broadband voice services offered by cable multiple system operators, competitive LECs (CLECs), satellite operators, and other broadband service providers. However, they also desire the reliability and emergency support afforded by their POTS service.